How Wireless Intercoms for Automatic Gates work
Wireless Audio and Video
Wireless Intercoms have the advantage of not requiring any wiring between the gate or door and the house or office, which simplifies installation considerably in a lot of cases but how well do they work? Well it depends on a number of factors most wireless intercoms these days work on the same frequency (2.4Ghz) as WiFi, Blue tooth and Cordless phones so must be compatible with these otherwise they simply won't work well enough because of interference from these systems. Some Intercoms use other frequencies 27Mhz, 49Mhz, 900Mhz or 1.9Ghz, which shouldn't give any problems because these aren't as widely used as 2.4Ghz, 2.4Ghz wireless intercoms that have anti-interference and digital frequency hopping and encryption technology generally will work up to 300m in open air or less if there's objects in the way such as a metal posts or anything with metal in it as this will reduce range considerably, whereas timber, thin brick and concrete (without reinforcing steel) won't so much. Trees will reduce range quite a bit when its raining because the water suspend in the leaves has an effect. The more objects in the path the more the range will be reduced. Wireless intercoms will not work through hills or other very dense objects. If the outdoor station is to be installed on a metal post you will need an antenna installed at the top of the post and away from any other metal around it, because this will reduce the range considerably.
Wiring is normally still needed between the Outdoor Station and the Gate Motor, which not only provides power to the outdoor station but also allows it to activate the gate. If a wireless system is used for a pedestrian gate or entry door with an electric lock it will need a power source from somewhere that generally means having to install cabling to where ever power is available. This cabling can be low voltage and may not necessarily go all the way to the inside station so significant cost savings can still be made.
External Antennas to Improve Range
If a wireless Intercom has the option of an external Antenna then this can be placed above or beyond obstructions to improve the range. An omni directional antenna is normally a small rod style antenna from 3 to 20cm long and will work in all directions. Some omin directional antennas have a higher gain than others, which will give better working range. Gain is specified in db, an antenna with a gain of 12db will work a lot further than one rated for 3db but is likely to be much larger physically so may not help with the appearance of the installation so much.
A directional antenna is either a flat panel, long array or metal rods, a grid or dish. These work in one direction only and also have different gains although a directional antenna with low gain has a wider working angle and shorter working range than those with a higher gain who have a narrower working angle but longer range.
If the intercom is a long way from the house and doesn't have any hills or dense objects in the way then a high gain directional antenna can be installed at each end, one on the roof of a building and the other on the gate post so a narrow beam is created to allow much longer range between these two points. If there is a dense object on the way the antenna needs to be installed high enough or in a position where it "sees" over or past the object. A wireless intercom can be made to work up to 1km with two 25db dish antennas.